1. Field of the Invention
This invention relates to improvements in a method of producing an airbag of an airbag restraint system which protects a passenger from a second impact inside a vehicle, such as automotive vehicle, upon the inflation of the airbag in the event of a vehicle collision. The airbag is normally disposed in its folded state in front of the passenger.
2. Description of the Prior Art
An airbag of an airbag restraint system is usually disposed in its folded state inside a padded steering wheel or an instrument panel located in front of a vehicle passenger. In the event of a vehicle collision, an inflator or gas generator is operated in response to a collision signal from a collision sensor and discharges gas which is supplied under pressure into the folded airbag. Then, the airbag inflates and develops toward the vehicle passenger, who is moving forward under inertia, thereby softly restraining the passenger to protect the passenger from coming into direct contact with either the steering wheel and/or the windshield.
An example of the airbag is arranged as follows: The airbag is made of front and rear side cloths which are sewn at their peripheral portion with each other to form a bag-shaped arrangement. The thus formed airbag is turned inside out so that a sewn portion is located inside the airbag. The rear side cloth is formed at its central part with a hole in which a part of the inflator is disposed. The airbag is fixed at its peripheral portion around the hole to the inflator to maintain a gas tight seal by means of rivets or the like.
High pressure gas directly strikes against the front side cloth upon operation of the inflator, and therefore the whole inside surface of the front side cloth is coated with a coating of a resinous material such that it becomes heat resistant and gas tight. Additionally, concerning the rear side cloth, the same resinous material is coated at the peripheral portion and the central portion thereby to prevent fraying of the peripheral and central portions of the rear side cloth. At the peripheral portion, the rear side cloth is sewed to the front side cloth. At the central portion formed with the hole for the inflator, the rear side cloth is fixed to the inflator by using the rivets or the like.
However, drawbacks have been encountered in the production process of the above-discussed conventional airbag, as set forth below. That is, the production process requires a sewing step for the front and rear side cloths upon forming the resinous coating on the front and rear side cloths. Additionally, the resinous coating is required to be formed at the peripheral portion with a predetermined width and at the central portion with a predetermined width larger than the hole for the inflator, thereby making it difficult to carry out a continous coating operation. Thus, the production process of the airbag is complicated and disadvantageous from a point of view of production cost.